What if your child can't manage to cry loudly?

26 February 2026 Research news item

Engaging with your baby is essential from the very first day. A simple glance, a warm smile, or soft coos are the initial building blocks of connection and bonding, fostering development for both parent and child. But what happens when your baby struggles to express those signals? How can you figure out what your little one needs?

Behavioural scientist Linda Reus is dedicated to supporting parents whose children face developmental challenges. She specialises in working with hypotonic children: those born with low muscle tone, often making it hard for them to move, make sounds, show facial expressions, or respond to touch. While medical research tends to focus on the various causes of hypotonia, Reus emphasises that there is a significant lack of attention on how parents can foster meaningful interactions with their children and better understand their unique needs. These interactions are vital, as hypotonic children frequently experience social and emotional behavioural issues, including struggles in forming friendships and expressing themselves. That’s why Reus has shifted her research focus to this critical area, with full support from the Radboud Fund.

Causes of hypotonia

Issues within the central nervous system, such as oxygen deprivation at birth, genetic syndromes, or brain abnormalities, are the leading causes of hypotonia. Reus focused his doctoral research on Prader-Willi syndrome, a neurological disorder that causes children to be born with severe hypotonia, and this muscle weakness often continues throughout their development. "Thanks to pediatric physical therapy, speech therapy, and occupational therapy, we’re now able to offer these children strong support to help them develop physically to the best of their ability," says Reus.

dr. Linda Reus

When engaging with these children, you need to slow everything down, much slower than you might be accustomed to, and then slow it down even more

During her research, Reus frequently heard parents express a similar sentiment: “If I could do it over, I would have focused much more on social-emotional development.” This statement resonated with her deeply.

Communicating in slow motion

Children with hypotonia often find it challenging to develop social skills because their surroundings may not respond to their needs effectively. After years of research, Reus played a key role in creating Beweging als Houvast (Movement as a Guide), a method designed to teach professionals how to foster meaningful interactions through careful movement and pacing. “When working with these children, you need to slow everything down, much slower than you might be accustomed to, and then slow it down even more,” explains Reus. For children with hypotonia, opportunities for interaction are considerably limited. Reus is now eager to explore whether this method can also enhance the parent-child relationship and what positive effects it might yield for the child.

What’s next?

So, it's time to get started! In the initial phase of her research, Reus plans to guide fourteen parent-child pairs (online) using the Beweging als Houvast method. Her goal is to teach them how to slow down and connect with their child, tapping into that essential moment for meaningful interaction. Following this, she intends to showcase the method's effectiveness on a broader scale, ensuring that every parent of a child with hypotonia can access this support as a standard resource. “Every parent deserves this help,” Reus emphasises.

Ellen Doomernik

The Radboud Fund

Ellen Doomernik, a fundraiser at the Radboud Fund, agrees. The Radboud Fund enables groundbreaking research through donations from organisations and individuals. “Because this research falls between medical and non-medical, it was quite difficult to fund,” says Doomernik. Most funding goes to treatments and research into the underlying condition. But Reus’s research is about improving the development of children with the condition. The Radboud Fund connected several funds to the project, including the Prader-Willi Fund and the JKF Children’s Fund. Thanks to this, the research can start on March 16.

A rare condition with immense impact

Babies with severe hypotonia are rare, fortunately. But for the families affected, the impact is immense. What these children need most is often the least obvious: not just medical interventions, but people who can read and follow them. Thanks to Reus’s research, that change may come soon.

Three tips for parents of a baby with hypotonia

Are you a parent of a child with hypotonia? Reus already has three tips for you:

Slow down, even more than you think is necessary.
Do something, then wait for your child to respond, however small, before continuing.
Keep cuddling, even if it seems to have little effect. There is an effect, just in a different way and often delayed.

Contact information

Contact: Dr L. Reus (Linda)
Organizational unit: Faculty of Social Sciences, Radboud Centre Social Sciences, Behavioural Science Institute
About person: Dr L. Reus (Linda) , E.A.A.M. Doomernik (Ellen)
Theme: Behaviour, Upbringing, Health & Healthcare